Download Lecture 4 Tissues V10

Chapter 4
Tissue:
The Living
Fabric
9/8/2015
© Annie Leibovitz/Contact
Press Images
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Nervous tissue: Internal communication
• Brain
• Spinal cord
• Nerves
Muscle tissue: Contracts to cause movement
• Muscles attached to bones (skeletal)
• Muscles of heart (cardiac)
• Muscles of walls of hollow organs (smooth)
Epithelial tissue: Forms boundaries between different
environments, protects, secretes, absorbs, filters
• Lining of digestive tract organs and other hollow
organs
• Skin surface (epidermis)
Connective tissue: Supports, protects, binds
other tissues together
• Bones
• Tendons
• Fat and other soft padding tissue
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4.2 Epithelial Tissue
• Epithelial tissue (epithelium) is a sheet of
cells that covers body surfaces or cavities
• Two main forms:
– Covering and lining epithelia
• On external and internal surfaces (example: skin)
– Glandular epithelia
• Secretory tissue in glands (example: salivary glands)
• Main functions: protection, absorption, filtration,
excretion, secretion, and sensory reception
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Special Characteristics of Epithelial Tissues
• Epithelial tissue has five distinguishing
characteristics:
1.
2.
3.
4.
5.
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Polarity
Specialized contacts
Supported by connective tissues
Avascular, but innervated
Regeneration
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Classification of Epithelia
• All epithelial tissues have two names
– First name indicates number of cell layers
• Simple epithelia are a single layer thick
• Stratified epithelia are two or more layers thick and
involved in protection (example: skin)
– Second name indicates shape of cells
• Squamous: flattened and scale-like
• Cuboidal: box-like, cube
• Columnar: tall, column-like
– In stratified epithelia, shape can vary in each
layer, so cell is named according to the shape in
apical layer
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Figure 4.2a Classification of epithelia.
Apical surface
Basal surface
Simple
Apical surface
Basal surface
Stratified
Classification based on number of
cell layers.
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Figure 4.2b Classification of epithelia.
Squamous
Cuboidal
Columnar
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Classification based on cell shape.
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Figure
Epithelial
tissues.
Simple4.3a
squamous
epithelium
Description: Single layer of
flattened cells with disc-shaped
central nuclei and sparse
cytoplasm; the simplest of the
epithelia.
Air sacs of
lung tissue
Nuclei of
squamous
epithelial
cells
Function: Allows materials to
pass by diffusion and filtration
in sites where protection is not
important; secretes lubricating
substances in serosae.
Location: Kidney glomeruli;
air sacs of lungs; lining of heart,
blood vessels, and lymphatic
vessels; lining of ventral body
cavity (serosae).
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Photomicrograph: Simple squamous
epithelium forming part of the alveolar
(air sac) walls (140×).
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Figure
Epithelial
tissues.
Simple4.3c
columnar
epithelium
Description: Single layer of tall
cells with round to oval nuclei; many
cells bear microvilli, some bear cilia;
layer may contain mucus-secreting
unicellular glands (goblet cells).
Microvilli
Simple
columnar
epithelial
cell
Function: Absorption; secretion
of mucus, enzymes, and other
substances; ciliated type propels
mucus (or reproductive cells) by
ciliary action.
Location: Nonciliated type lines
most of the digestive tract (stomach
to rectum), gallbladder, and excretory
ducts of some glands; ciliated variety
lines small bronchi, uterine tubes,
and some regions of the uterus.
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Mucus of
goblet cell
Photomicrograph: Simple columnar
epithelium of the small intestine mucosa
(640×).
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Figure
4.3e
Epithelial
Stratified
squamous
epitheliumtissues.
Description: Thick membrane
composed of several cell layers;
basal cells are cuboidal or columnar
and metabolically active; surface
cells are flattened (squamous); in the
keratinized type, the surface cells are
full of keratin and dead; basal cells
are active in mitosis and produce the
cells of the more superficial layers.
Stratified
squamous
epithelium
Nuclei
Basement
membrane
Connective
tissue
Function: Protects underlying
tissues in areas subjected to
abrasion.
Location: Nonkeratinized type forms
the moist linings of the esophagus,
mouth, and vagina; keratinized variety
forms the epidermis of the skin, a dry
membrane.
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Photomicrograph: Stratified squamous
epithelium lining the esophagus (285×).
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4.3 Connective Tissue
• Connective tissue is the most abundant and
widely distributed of primary tissues
• Major functions: binding and support, protecting,
insulating, storing reserve fuel, and transporting
substances (blood)
• Four main classes
– Connective tissue proper
– Cartilage
– Bone
– Blood
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Table 4.1-1 Comparison of Classes of
Connective Tissues
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Table 4.1-2 Comparison of Classes of
Connective Tissues (continued)
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Major Functions of Connective Tissue
•
•
•
•
•
Binding and support
Protecting
Insulating
Storing reserve fuel
Transporting substances (blood)
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Common Characteristics of Connective
Tissue
• Three characteristics make connective tissues
different from other primary tissues:
– All have common embryonic origin: all arise from
mesenchyme tissue as their tissue of origin
– Have varying degrees of vascularity (cartilage is
avascular, bone is highly vascularized)
– Cells are suspended/embedded in extracellular
matrix (ECM) (protein-sugar mesh)
• Matrix supports cells so they can bear weight,
withstand tension, endure abuse
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Structural Elements of Connective Tissue
(cont.)
• Connective tissue fibers
• Three types of fibers provide support
– Collagen
– Elastic fibers
– Reticular
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Structural Elements of Connective Tissue
(cont.)
• Cells
– “Blast” cells
• Immature form of cell that actively secretes ground
substance and ECM fibers
• Fibroblasts found in connective tissue proper
• Chondroblasts found in cartilage
• Osteoblasts found in bone
• Hematopoietic stem cells in bone marrow
– “Cyte” cells
• Mature, less active form of “blast” cell that now
becomes part of and helps maintain health of matrix
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Structural Elements of Connective Tissue
(cont.)
• Other cell types in connective tissues
– Fat cells
• Store nutrients
– White blood cells
• Neutrophils, eosinophils, lymphocytes
• Tissue response to injury
– Mast cells
• Initiate local inflammatory response against foreign
microorganisms they detect
– Macrophages
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• Phagocytic cells that “eat” dead cells, microorganisms;
function in immune system
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Extracellular
Cell types
Figure
4.7 Areolar connective tissue:
A
matrix
prototype (model) connective tissue.
Ground substance
Macrophage
Fibers
• Collagen fiber
• Elastic fiber
• Reticular fiber
Fibroblast
Lymphocyte
Fat cell
Capillary
Mast cell
Neutrophil
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Figure
4.8btissue
Connective
tissues.
Connective
proper: loose connective
tissue, adipose
Description: Matrix as in
areolar, but very sparse; closely
packed adipocytes, or fat cells,
have nucleus pushed to the
side by large fat droplet.
Nucleus of
adipose
(fat) cell
Function: Provides reserve
food fuel; insulates against
heat loss; supports and
protects organs.
Fat droplet
Location: Under skin in
subcutaneous tissue; around
kidneys and eyeballs; within
abdomen; in breasts.
Adipose
tissue
Photomicrograph: Adipose tissue from the
subcutaneous layer under the skin (350×).
Mammary
glands
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Figure
4.8g
Connective tissues.
Cartilage:
hyaline
Description: Amorphous but
firm matrix; collagen fibers form
an imperceptible network;
chondroblasts produce the
matrix and when mature
(chondrocytes) lie in lacunae.
Chondrocyte
in lacuna
Function: Supports and
reinforces; serves as resilient
cushion; resists compressive
stress.
Matrix
Location: Forms most of the
embryonic skeleton; covers the
ends of long bones in joint
cavities; forms costal cartilages
of the ribs; cartilages of the
nose, trachea, and larynx.
Photomicrograph: Hyaline cartilage from
a costal cartilage of a rib (470×).
Costal
cartilages
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Figure 4.8h Connective tissues.
Cartilage: elastic
Description: Similar to hyaline
cartilage, but more elastic
fibers in matrix.
Chondrocyte
in lacuna
Function: Maintains the shape
of a structure while allowing
great flexibility.
Matrix
Location: Supports the
external ear (pinna); epiglottis.
Photomicrograph: Elastic cartilage from the
human ear pinna; forms the flexible skeleton
of the ear (800×).
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Figure 4.8i Connective tissues.
Cartilage: fibrocartilage
Description: Matrix similar to
but less firm than that in hyaline
cartilage; thick collagen fibers
predominate.
Function: Tensile strength
allows it to absorb compressive
shock.
Chondrocytes
in lacunae
Location: Intervertebral discs;
pubic symphysis; discs of knee
joint.
Collagen
fiber
Intervertebral
discs
Photomicrograph: Fibrocartilage of an
intervertebral disc (125×). Special staining
produced the blue color seen.
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Figure
4.8j
tissues.
Others:
bone Connective
(osseous tissue)
Description: Hard, calcified
matrix containing many
collagen fibers; osteocytes
lie in lacunae. Very well
vascularized.
Central
canal
Lacunae
Function: Supports and
protects (by enclosing);
provides levers for the muscles
to act on; stores calcium and
other minerals and fat; marrow
inside bones is the site for
blood cell formation
(hematopoiesis).
Lamella
Location: Bones
Photomicrograph: Cross-sectional view of
bone (125×).
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Figure 4.8k Connective tissues.
Connective tissue: blood
Description: Red and white
blood cells in a fluid matrix
(plasma).
Function: Transport
respiratory gases, nutrients,
wastes, and other substances.
Red blood
cells
(erythrocytes)
White blood
cells:
• Lymphocyte
• Neutrophil
Location: Contained within
blood vessels.
Plasma
Photomicrograph: Smear of human blood (1670×);
shows two white blood cells surrounded by red
blood cells.
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4.4 Muscle Tissue
• Highly vascularized
• Responsible for most types of movement
– Muscle cells possess myofilaments made up of
actin and myosin proteins that bring about
contraction
• Three types of muscle tissues:
– Skeletal muscle
– Cardiac muscle
– Smooth muscle
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Figure 4.9a Muscle tissues.
Skeletal muscle
Description: Long, cylindrical,
multinucleate cells; obvious
striations.
Part of
muscle
fiber (cell)
Function: Voluntary movement;
locomotion; manipulation of the
environment; facial expression;
voluntary control.
Nuclei
Location: In skeletal muscles
attached to bones or
occasionally to skin.
Striations
Photomicrograph: Skeletal muscle (440×).
Notice the obvious banding pattern and the
fact that these large cells are multinucleate.
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Figure
4.9b
Muscle tissues.
Cardiac
muscle
Description: Branching,
striated, generally uninucleate
cells that interdigitate at
specialized junctions
(intercalated discs).
Intercalated
discs
Function: As it contracts,
it propels blood into the
circulation; involuntary control.
Striations
Nucleus
Location: The walls of the
heart.
Photomicrograph: Cardiac muscle (475×);
notice the striations, branching of cells, and
the intercalated discs.
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Figure
4.9c
Muscle tissues.
Smooth
muscle
Description: Spindle-shaped
(elongated) cells with central
nuclei; no striations; cells
arranged closely to form sheets.
Nuclei
Function: Propels substances
or objects (foodstuffs, urine,
a baby) along internal
passageways; involuntary
control.
Location: Mostly in the walls
of hollow organs.
Smooth
muscle
cell
Photomicrograph: Sheet of smooth muscle
from the digestive tract (500×).
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4.5 Nervous Tissue
• Main component of nervous system (brain,
spinal cord, nerves)
– Regulates and controls body functions
• Made up of two specialized cells:
– Neurons: specialized nerve cells that generate
and conduct nerve impulses
– Neuroglia: supporting cells that support,
insulate, and protect neurons
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Figure
4.10 Nervous tissue.
Nervous tissue
Description: Neurons are
branching cells; cell processes
that may be quite long extend
from the nucleus-containing
cell body; also contributing to
nervous tissue are nonexcitable
supporting cells.
Neuron processes
Cell body
Nuclei of
supporting
cells
Axon Dendrites
Cell body
of a neuron
Function: Neurons transmit
electrical signals from sensory
receptors and to effectors
(muscles and glands); supporting
cells support and protect neurons.
Neuron
processes
Location: Brain, spinal
cord, and nerves.
Photomicrograph: Neurons (350×)
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